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zimovet [89]
3 years ago
15

john is twice as old as mary. the sum of their ages is 21. how old is mary? let j = john's age and m = mary's age. select the sy

stem equations that represents the problem.
Mathematics
1 answer:
Verdich [7]3 years ago
3 0
Hello,

let's assume j the john's age, m the mary's age.

<span>"John is twice as old as mary"==>j=2*m
</span>
<span>"the sum of their ages is 21" ==>j+m=21

==>2*m+m=21
==>3m=21
==>m=7
and j=21-7=14

</span>
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9 hundred equals how many tens
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Answer:

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Step-by-step explanation:

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Step-by-step explanation:

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Wewaii [24]

Answer:  

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Step-by-step explanation:

Concentration            Amount of             Amount

of Solution                   Solution (L)             of Acid

    15%                                x                         0.15x

    33%                               y                         0.33y

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8 0
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